With the introduction and subsequent market penetration of light cured composite compounds used for Class 2 restorative dentistry, significant gains were made in the structural quality, natural appearance, and longevity of restorative dental work. However, at the same time, a new curve was thrown at the dentist. Unlike the older traditional amalgam fillings, once a composite filling was successfully placed and shaped, the dentist was still not finished. In an effort to completely polymerize the compound and to try to assure a problem free placement, the dentist would cure the compound with an intense light of a prescribed wavelength. A majority of the early curing lights that were used to achieve this function utilized a halogen based incandescent lamp as the light source. The technology was simple and relatively affordable but it was a bit “power hungry”, and produced a high degree of waste heat, both at the lamp and at the tooth being treated. Design refinements to optically filter the wavelengths of the energy that were actually delivered to the tooth significantly reduced the unnecessary heating of the tooth. This was a helpful refinement as the conventional photo activators used to induce cross-polymerization of most restorative compounds only utilize a portion of the blue light spectrum. By filtering out much of the Green, Red, and Infra-Red portions of the light being delivered to the tooth, advancements were made toward eliminating a majority of the unrequired wavelengths that result in nothing more than “waste heat” at the tooth. Typical curing times for a tooth restoration with light cured composites was in the range of 20 to 60 seconds.
Then, in the mid to late 1990s, came the dawn of the blue high brightness LED, and not too long thereafter, the rise of the blue LED curing wand. Blue LEDs that emitted light in the 450 to 485 nanometer wavelength range were well suited, spectrally at least, for the curing of dental composites. Power capabilities and pricing of the new blue LEDs were a limiting factor for several years—well into the new millennia. However, it was not long until LED curing wands providing a reliable 200-300 mW/cm2 (milliwatts per sq. centimeter) were technically viable and commercially available. This allowed introduction of small hand-held battery operated curing lights that could perform 20-60 second composite cure times similar to their older cord based halogen predecessors.
Conventional LED curing wands have advanced significantly beyond the capabilities of the initial blue LED curing wand. There are now hand-held battery operated curing lights capable of producing in excess of 10 times their predecessor's power—many at 3,200 mW/cm2 or more, and some now as high as 8,000 mW/cm2. This results in a curing light that can, in theory, cure a composite placement in a mere 1 to 3 seconds by delivering the target amount of total optical energy (usually measured in Joules) in less than one tenth the time. These advancements, however, are not without downsides.
Some conventional dental light wands operate with means for testing the optical output, such as in the base of the charging stand. However, there is no feedback mechanism incorporated into such a dental light wand, itself.
Conventional LED based curing lights have progressed to address several concerns over the past many years with respect to cordless operation, user ergonomics, digitally controlled exposure times and much higher optical power availabilities. However, these improvements have done little to eliminate many of the causes or issues, such as user variances, that often times prevent safe, repeatable, and reliable compound cures. And, in some respects, the significantly higher power levels of recent curing lights have allowed more frequent over-exposure, which may affect the ability to achieve enhanced safety and repeatable and reliable compound cures.